RE: Byron A-4 Skyhawk EDF conversion  
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RE: Byron A-4 Skyhawk EDF conversion - 3/21/2009 10:40 PM   
Greg Covey



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Status: offline 		I modified a new Byron thrust tube from Iron Bay Model Company to fit the smaller diameter needed for the E-Turbax. The dimensions are as follows:
  • Length: 27.5"
  • DF end 4.88" diameter (x Pi = 15.3" circumference)
  • Output 3.75" diameter (x Pi = 11.8" circumference)

A 5" hose clamp will hold the thrust tube in place around the EDF and a hole will be cut about an inch back from the motor to drop the wires through.

Note that an output diameter of 3.5" would favor top end speed while a diameter of 4.0" would favor thrust. The recommended compromise between thrust and speed is 3.75". This is where I decided to start and we'll see just how much of our 600' long field length is needed for take-off.

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< Message edited by Greg Covey -- 3/22/2009 7:38 PM >

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RE: Byron A-4 Skyhawk EDF conversion - 3/22/2009 7:23 PM   
Greg Covey



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Status: offline 		The E-turbax unit was mounted to the plywood former using #8-32 hex head screws, washers, and t-nuts. I used both lock washers and Locktite to keep things secure.

After sliding the thrust tube through the tail, I routed the motor wires through the hole in the tube and snugged it onto the E-Turbax unit. The tube was held in place with several pieces of clear shipping tape and a lightly-tightened 5" hose ring.

The result is a very clean thrust output channel with the motor wires tightly secured as a bundle.

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< Message edited by Greg Covey -- 3/24/2009 12:40 AM >

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RE: Byron A-4 Skyhawk EDF conversion - 3/26/2009 12:24 AM   
Greg Covey



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Status: offline 		To close the gap between the thrust tube and the fiberglass body, I made a custom "ring" of foam that fills the gap and stabilizes the tube. I cut a 1-1/2" wide plastic ring from a CD case cover which is about 5" in diameter and then custom glued it to just fit around the 3-3/4" thrust tube end. I then glued a thin 1-1/2" strip of foam to this thicker plastic ring made from the CD case and pressed it in place. In this manner, the thrust tube does not get distorted by the foam. It is held by double-side tape between the plastic ring and the thrust tube so it cannot slip.

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< Message edited by Greg Covey -- 3/26/2009 12:26 AM >

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RE: Byron A-4 Skyhawk EDF conversion - 3/26/2009 1:24 PM   
f16man


 

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Status: offline 		Looks pretty cool, it will be interesting where the batteries will have to be for the cg and what the all up ready to fly weight will be . Looks like you are getting close to flying time !!!

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RE: Byron A-4 Skyhawk EDF conversion - 3/26/2009 10:39 PM   
Greg Covey



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Status: offline 		The weather has been very Spring-like here this week and it helps to inspire me. The battery packs should be in stock any day now but I will likely use my existing 6-cell 5000mAh packs to start my placement search. Both pack pairs weigh about 3.2lbs.

I started holding down the control and motor wires with some homemade balsa pieces and CA. The other set of servo control wires is held in place with some 3M cord clips. The CC HV110 ESC is secured by both a Velcro plywood plate and a Velcro "seat belt". I can pick up the entire jet by the ESC so it is secured well and resides in the secondary air flow out of the way of the primary air flow for power.

Once the wires were secured, I created an air intake scoop from a large plastic funnel I bought at an Ace Hardware store. The scoop directs all air from the 9" fuselage to the 5-1/8" E-Turbax opening. The photo shows it sitting in position but not yet mounted.

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< Message edited by Greg Covey -- 3/26/2009 10:50 PM >

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RE: Byron A-4 Skyhawk EDF conversion - 3/29/2009 4:47 PM   
Greg Covey



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Status: offline 		Since the intake scoop is held in three places by the fuselage body, a single aluminum bracket was used to secure it to the former with #8-32 hardware.

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RE: Byron A-4 Skyhawk EDF conversion - 3/29/2009 8:25 PM   
Greg Covey



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Status: offline 		To safely power the A-4, I am using a Duralite Flight Systems 6v regulator with a built-in fail-safe On/Off switch. The regulator supplies 6.0 volts at 7.5amps continuous current with spikes up to 10amps. If the switch fails, the regulator remains on.

The regulator is fed by a 3oz, 2-cell Kokam 1500mAh pack which I modified to use the FMA Cellpro Multi4 charger. Likewise, my new 6-cell FlightPower EON28 packs with be charged by two Cellpro 10s chargers. These chargers provide safe balanced charging at up to a 3C rate. My 6s 4950mAh EON28 packs can be charged at a 2C rate on the Cellpro 10s charger for a 30-minute charge time.

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< Message edited by Greg Covey -- 3/29/2009 8:42 PM >

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RE: Byron A-4 Skyhawk EDF conversion - 4/2/2009 3:10 AM   
zlin50ls



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Status: offline 		Skyhawknut, I like your A-4 EDF project. Have you come across anyone doing an EDF conversion on the Byron F-86? I'm looking to put a EDF unit into one and wondered if this has already been done.

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RE: Byron A-4 Skyhawk EDF conversion - 4/2/2009 7:42 PM   
skyhawknut


 

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Status: offline 		Yes - the F-86 has been done. There was one for sale here a while back with the electric conversion, though I never saw a build or flight report for it.

There are 2 that have been done over at RCG. One flown and one awaiting good weather for it's first flight.

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RE: Byron A-4 Skyhawk EDF conversion - 4/2/2009 11:55 PM   
zlin50ls



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Status: offline 		Thanks for the reply. I knew someone had thought about this also, now that there are suitable EDF units on the market. These older Byron DF kits are a great way to get airborne without the high cost of new over-priced EDF jet kits. Thanks again.

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RE: Byron A-4 Skyhawk EDF conversion - 4/3/2009 12:45 AM   
Greg Covey



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Status: offline 		I thought that I would take some photos of the assembled A-4 since I was testing where to place the two 6s packs for proper CG. Note the tape lines on the top of the wing where the plane previously balanced with the original glow-powered setup. I used the original cockpit since the canopy glue was still drying on my new one.

I discovered that the packs will fit nicely in the jet. One is placed up front in the nose and can be accessed via the nose wheel opening. The other pack will be placed just behind the main former that supports the nose gear and can easily be accessed via the cheater hole. We will likely end up reducing, or even eliminating, the original cheater hole with a removable cover.

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< Message edited by Greg Covey -- 4/3/2009 12:50 AM >

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RE: Byron A-4 Skyhawk EDF conversion - 4/3/2009 1:26 PM   
f16man


 

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Status: offline 		Have you checked out the weight yet? The A-4 was always my favorite as i grew up in sunnyvale ca. about 3 miles from moffet field. in the 60s and 70s we always had the blue angels buzzing the town, that was before all the tree huggers moved in to work at all the wafer fab companies.

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RE: Byron A-4 Skyhawk EDF conversion - 4/3/2009 9:42 PM   
Greg Covey



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Status: offline 		Here is what I measured for the weights:
  • Main Fuselage = 145oz (9.06lbs)
  • Wings w/Retracts = 44oz (2.75lbs)
  • Two 6s 5AH EON Batteries = 51oz (3.2lbs)

The plane without e-fuel is 189oz (11.8lbs). The total RTF weight is 240oz (15lbs).

< Message edited by Greg Covey -- 4/3/2009 9:45 PM >

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RE: Byron A-4 Skyhawk EDF conversion - 4/4/2009 4:32 PM   
f16man


 

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Status: offline 		Should fly good can't wait for the video!!!!!!!!!!!!!!!!!!!!!!!!!!

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RE: Byron A-4 Skyhawk EDF conversion - 4/6/2009 10:10 PM   
Greg Covey



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Status: offline 		I created a plywood platform for the aft LiPo pack which is secured by industrial strength Velcro on the bottom side and then wrapped in a Velcro "seat belt". The plywood platform was then epoxied to the hardwood runners from the main former that holds the hose gear assembly.

Shown in the photos is a 5-cell 5AH FlightPower EVO pack. The new EON packs will be 6-cells.

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< Message edited by Greg Covey -- 4/6/2009 10:13 PM >

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RE: Byron A-4 Skyhawk EDF conversion - 4/7/2009 11:00 PM   
Greg Covey



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Status: offline 		I made some bottom covers out of several layers of material so that it was solid, easy to remove, and somewhat matched the color scheme.

The inside layer is Coroplast which is simply taped into position and either slides on top of the aileron servo bottoms or the funnel bracket. The outside layer is thin balsa that I covered with an off-white shrink film. I replaced the weak and ugly green fiberglass brace with a solid plywood brace. The EDF hatch is then screwed into the plywood brace and the cheater hole hatch is simply taped in position since it cannot be pushed back or pull up.

Notice that I covered half of the original cheater hole as a starting point. It allows the aft battery pack to still be accessible and I ramp the air (not shown) right into the funnel.

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< Message edited by Greg Covey -- 4/7/2009 11:09 PM >

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RE: Byron A-4 Skyhawk EDF conversion - 4/8/2009 9:36 PM   
Willit Run 353



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Status: offline 		thats amazing!! what diameter is your fan and where can you get one of those from.

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RE: Byron A-4 Skyhawk EDF conversion - 4/18/2009 4:55 AM   
preditor


 

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Status: offline 		Greg I've been looking for a byron a-4 for a while. Do you know anyone who has one to sell?

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RE: Byron A-4 Skyhawk EDF conversion - 4/19/2009 4:17 AM   
lauterbacher


 

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Status: offline 		When are those batterys coming in for you so we can see your testing?

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RE: Byron A-4 Skyhawk EDF conversion - 4/20/2009 3:57 PM   
Greg Covey



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Status: offline 		I don't know anyone who is selling a Byron A-4 at this time. Maybe you can post a wanted ad in the RCU marketplace. I think Iron Bay still sells the complete kit.

My EON packs have been pushed back from mid-April to late May so I am looking for an alternate to get things going in May.

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RE: Byron A-4 Skyhawk EDF conversion - 4/20/2009 7:19 PM   
lauterbacher


 

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Status: offline 		You should buy a couple othe XPS packs that are out and talked about on R/C Groups. take care

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RE: Byron A-4 Skyhawk EDF conversion - 4/26/2009 2:19 PM   
Greg Covey



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Status: offline 		I've decided to wait for the new EON packs because they should be in stock around mid-May. I can still have them for my scheduled maiden flight on Memorial Day weekend.

I came up with a convenient way to arm the 12s LiPo power system on the Byron EDF conversion which eliminates any spark. By touching the 100ohm 1w resistor lead to the + side of the HV110 ESC and then sliding the 6mm gold bullet connector in place, the spark is eliminated. In this manner, I can keep my new EON packs unmodified and not add any additional connectors or switches. The main red ESC wire sits in a safe channel so it doesn’t move around but the exposed resistor wire can also be easily covered with a piece of tubing, once the system is armed. The paper in the photo is positioned to make the connectors easier to see.

Resistors like this can be purchased at many places. Mine cost $0.053 from Newark Electronics On-line.

Specifications:
  • Newark Part No: 71M1113
  • Metal Film Resistor
  • Power Rating: 1W
  • Resistance Tolerance: 1%
  • Series:CCF60
  • Voltage Rating:500VDC


Note in the photo that my Rx. battery pack connector can now be secured in place, for flight, using a slightly cut servo connector clip. It is not shown in the photo with the clip in place.

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< Message edited by Greg Covey -- 4/26/2009 2:34 PM >

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RE: Byron A-4 Skyhawk EDF conversion - 4/27/2009 8:42 PM   
lauterbacher


 

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Status: offline 		Whats so special about these eon packs your getting, just curiosity?

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RE: Byron A-4 Skyhawk EDF conversion - 4/28/2009 1:55 PM   
Greg Covey



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Status: offline 		You can read about the new EON chemistry here. Basically, the EON packs provide 10% more power and 40% longer cycle life over previous generations of LiPo packs...effectively giving you a better investment. If I have any problem at all with my FlightPower packs, they can be checked out and serviced right here in the U.S.


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RE: Byron A-4 Skyhawk EDF conversion - 5/4/2009 10:58 PM   
Greg Covey



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Status: offline 		I did some preliminary testing at the field last weekend on the Byron A-4 EDF conversion when I went to test fly another review plane. My buddy snapped some photos of me showing off the spark-free arming and running some power tests.

Although I only had a 10s LiPo supply in the jet, two 5-cell EVO25 5AH packs, I was happy with the power level and low vibration. It was the first time I ran it up to full throttle and feel it is ready to go once we do some final air line securing and get my new 6s EON33 packs.

The guy with me is the pilot, and plane owner, Lynn Bowerman. Lynn will have his hands full landing the A-4 without flaps but he is a very accomplished pilot.

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< Message edited by Greg Covey -- 5/4/2009 11:02 PM >

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